This invention relates to elapsed time indicating devices and more particularly is concerned with a simple electrochemical timing cell which utilizes electrical current to anodize an electrode.
The prior art contains many examples of devices for measuring elapsed time by electrochemical means. One such system, such as described in U.S. Pat. No. 3,564,347 issued Feb. 16, 1971, employs dissimilar metal electrodes separated by an electrolyte which supports plating and/or deplating of ions at one of the metals. When one electrode is completely deplated with the metal of the other electrode, an electrochemical couple or voltage appears.
Another system providing a visual indication of elapsed time (offered by the Fredericks Company, Huntingdon Valley, Pa.) depends upon the plating out of copper ions from an electrolyte in a capillary tube as a function of current flow between anode and cathode.
Still another system, described in U.S. Pat. Nos. 3,045,178 issued July 17, 1962, and 3,665,308 issued May 23, 1972, provides a visual indication of elapsed time through the plating and deplating of two columns of mercury in a capillary tube separated by a small amount of electrolyte (a so-called gap) as a function of current flow.
These prior systems, while effective in certain applications, suffer from certain disadvantages. The dissimilar metal "switching" coulometers normally require expensive noble or rare metal elements and ions and are only suitable for indicating a specific "time-out" period--intermediate periods of time are not identifiable.
All of these systems depend upon the plating out of metallic ions.
It is an object of this invention to overcome the defects of prior elapsed time indicating devices.
It is a further object of this invention to produce a simple and low-cost elapsed time cell.
It is a still further object of this invention to provide an electrolytic cell that is capable of a continuous indication of elapsed time.
It is another object of this invention to provide a simple low-cost elapsed time indicator system.
It is yet another object of this invention to provide a low-cost elapsed time indicator system suitable for use in automobiles and other engine powered vehicles having a low voltage (e.g. 6 volt or 12 volt battery) source of electrical energy, which vehicles require special service maintenance at periodic running intervals.